Post #1512: Highest gasoline prices ever? Not really. Not even really close.


Source:  Calculated from Federal Reserve of St. Louis (FRED) data, series APU00007471A (gasoline) and CPIAUCSL (CPI), accessed 5/15/2022

In terms of the number of dollar bills you must surrender to purchase one gallon of gasoline, sure, gas is now at an all-time high within living memory.

But, as an economist, I have to point out that a dollar isn’t a dollar any more.  It used to be worth quite a bit more.  And because of that, it’s just plain stupid to look at long term price trends — or all time highs — in nominal dollars.

In real — that is, inflation-adjusted — terms, the current price of gas in the U.S. is nowhere near at an all-time high.  Within living memory.  That honor goes to June 2008, when the price of gas in the U.S. hit $5.46 per gallon, in today’s dollars.

For those of you old enough to recall, that was the period when West Texas Crude briefly hit $150 a barrel.  Which, inflation-adjusted, would be a cool $200 per barrel, in today’s dollars.  (Currently, West Texas is set at just a bit over $100 per barrel).

So when people talk about this being the highest price ever for gasoline in the U.S., my sole reaction is “bullshit”.  I’ve paid more than that, in real terms.  Most people now driving in the U.S. have paid more than that.  They just forget that period, and they don’t consider the dollar’s loss of value in the intervening decade and a half.

I guess I’m a true child of the 1970s.  I started driving amid the first and second Energy Crises / Arab oil embargoes.  Gasoline was rationed, and there was the real possibility that people in the U.S. Northeast were going to freeze to death due to the lack of an adequate supply of heating oil.

As a consequence, I drive gently, for best mileage.  I’ve always driven the highest-MPG car I could fit into, that I could afford.

So when I see some yahoo driving an F250 as his grocery-getter, moaning about the price of gasoline, I shed no tears.

Fact is, most people will not grasp the worth of crude oil until it’s all gone, or nearly.  Liquid fuels are really wonderful things to have around.  It’s not smart to squander them.

But, as a country, we will routinely haul three tons of future scrap metal down the highway, just to transport our sorry selves from Point A to Point B.

And to hell with the consequences.

Except when the price of gas goes up.  Then, suddenly, that’s serious.

Use this one clever trick to reduce belly fat increase MPG.

Two tricks, actually.  One that’s real, one that I only wish were real.

First, arguably the biggest eye-opener for me, when my wife bought a Prius back in 2005, was the real-time fuel economy gauge.  The car shows you what MPG you are getting, second-by-second.

Now, you’d think that a car with an EPA rating of 50 MPG would get 50 MPG, plus-or-minus, over the course of a drive.   But that’s not even remotely true.  The reality is that the MPG varies wildly from moment-to-moment, depending on what you’re doing.  A hard acceleration will push the MPG into the single digits (even in a Prius).  Coasting along, with the gas engine shut off, effectively generates infinite MPG.

The upshot is that the EPA rating of 50 MPG is the weighted average of all those different situations.  And it’s only the average.  Only when you are cruising at a steady speed on flat highway will you actually get 50 MPG.  Other times, you’re getting some MPG that’s not just different, but vastly different.

Back when the U.S. Congress still cared about gas mileage, there was a movement to mandate instantaneous MPG readouts on all new cars.  The reasoning — backed by plenty of research — was that if people could see that their driving style frequently drove their MPGs into the low-single-digit range, they’d change their behavior and improve their overall gas mileage.

Needless to say, the manufacturers of large, gas-guzzling vehicles — at that time, more-or-less the American automotive industry — fought against that.  If you make your profits on 3-ton SUVs that get 12 MPG, the last thing you want is for the owners to see just how rapidly those suck down gas during hard acceleration.

Today, some cars do have instantaneous MPG readouts on the dash.  But by and large, it’s not those big gas-guzzlers.  And by and larger, unlike the Prius, where the instantaneous MPG was front-and-center, those tend to look like an afterthought.

That said, in the modern era, with OBD-II (On-board diagnostics II) ports standard on all cars, it’s a snap to add an instantaneous fuel economy readout to any car.  Cheapest one I could find that is set up to do that runs about $80.  I used to use a ScanGauge in my non-Prius vehicle, which in addition to showing fuel economy will (e.g.) read and reset engine codes and such, for about $160.  And I”d bet that some of the cheaper bluetooth-enabled OBD readers — that work with your phone — will do that as well.

What I’m getting at here is that the best thing you can do about high gasoline prices is to use less.  Drive less, sure.  But drive to get better MPG as well.  And as a learning tool for that, nothing beats an instant-reading fuel economy gauge.  These days, those are straight-up plug-and-play with any modern car.

Separately, there’s one more thing I’d do to bring down U.S. gasoline consumption.  This one is completely imaginary.  But I’d bet it would be hugely effective.

Here’s something I’ve learned from using firewood to heat my home.  Unless you physically lift and carry your fuel, you have no clue about the tons and tons of fuel you are consuming to (e.g.) heat your home.  Or run your car.

If every able-bodied person had to fill their gas tank by hand — by lifting up a container and pouring in the gas — I bet that much of the U.S. demand for huge vehicles would disappear promptly.   Because, with gas pumps and such, the average American driver has no clue about the sheer weight of fuel that they consume every year.  And if you had to move all that weight, even a little ways, you’d think a lot harder about how much you need to drive, and how much vehicle you really need.

Take, say, a top-of-the-line 2018 GMC Yukon, big engine, 4WD.  That gets 16 MPG overall, per  The average U.S. driver drives about 14,000 miles a year (widely cited from the US Federal Highway Administration).  A gallon of gas weighs about 6.3 pounds (cite).

Put those numbers in a spreadsheet, and you’ll estimate that the typical Yukon driver pumps 2.8 tons of gasoline into the tank, every year.  With a curb weight of 5,965 pounds or just under 3 tons, (cite), in round numbers, a typical GMC Yukon consumes its own weight in gasoline every year.  Year after year.

And if you had to lift the weight of that vehicle, one piece at a time, week after week, over the course of a year, I expect you’d get pretty tired of it.  To the point where you might consider something a bit more efficient.  Even if you had no problem with the expense of buying and running a Yukon.

For sure, by the end of heating season each year, I am right sick of firewood.  And that’s a good thing, because it reminds me of the absolutely ridiculous quantities of fuel required to keep a typical suburban house heated.  And makes me just that much more aggressive about insulation, drafts, thermostat settings, and the like.

But the fact is, as Americans, we never have to lift a finger to get that fuel delivered.  (Or, at least, we never have to lift anything heavier than the nozzle of a gas pump).

And so, as with the instantaneous MPG of your vehicle, it’s your birthright as an American to be absolutely ignorant about the enormous quantities of fuel you consume.

Until the price goes up.  Then everybody seems surprised, and starts pointing fingers.

Having now seen several fuel price spikes in my lifetime, I no longer find the predictable responses to be even remotely amusing.  And I think that if we actually saw the amount of fuel being burned on a flow basis, and if each of us had to tote our own fuel around — even a little bit — we’d be a lot more careful about how we use it.

Post G22-016, rain barrel drip irrigation system, part I: KISS


I maintain eight 55-gallon rain barrels around my house, six of which I use to water my garden.

I used to pat myself on the back for doing my part for the Chesapeake Bay, by installing and maintaining those rain barrels.  Those barrels reduce runoff into the bay, and runoff is the principal source of the nitrogen and phosphorus nutrient overload in the Bay.  (Those nutrients dissolved in rain water come from air pollution, mostly from cars and power plants.  This is why reducing storm water runoff has been a principal focus of Chesapeake Bay Preservation Act.  See my post on bioretention for a quick overview of all that.)

Then I made the mistake of doing the math (Post G21-043, shown above).  As you can see from the right-hand column on the table above, my rain barrels, fed by about 850 square feet of roof area, are a drop in the bucket (far right column).  The six-barrel system for my garden diverts just 0.6% of the rain that falls on my yard.  Their impact on runoff is more-or-less rounding error.

The other odd aspect of rain barrels, shown in the table above, is that they are characterized by strongly diminishing returns.  Above, I  used actual local weather data to model an idealized 300-square-foot garden, watered by six 50-gallon barrels fed by 850 square feet of roof.  (Details are in Post G21-043).  For that setup, in Virginia, the first two rain barrels halve your use of municipal water for watering the garden.  Each year, those two barrels would save me a bit over $17 in municipal water and sewer costs.  The first two barrels plausibly they pay for themselves over their useful lifetime.  (Mine are recycled soda-syrup barrels, some of which are now in their their third decade of use as water barrels).

But the same model (850 square foot roof area, 300 gallons of barrels, 300 square foot garden, Virginia weather) shows that going from 10 barrels to 20 saves just over $2.50 in additional municipal water cost per year.  The un-discounted payback period for those barrels would be measured in centuries.

And that, in turn, is a fundamental aspect of the weather in this area:  When it rains, it pours.  If we’re getting consistent weekly rains, I don’t need the barrels, and they sit full.  But one hot summer week with no rain will drain them completely.  If I want to extend their useful life to two weeks of drought, I need another six barrels.  Which then are more-or-less idle for an even greater portion of the summer than the first six are.

Dual-pressure irrigation system?  Nope, use Theorem 1.

One thing that I am absolutely sure about, regarding rain barrels, is that I’m really tired of toting buckets and cans of water around.  To put one inch of water on (say) 300 square feet of raised beds, that’s 187 gallons of water that I must tote from the rain barrels to the garden.

I bought a small submersible pump for those days when I don’t much feel like carrying dozens of five-gallon buckets of water.  But it’s slow, particularly when attached to the length of hose required to get to the far reaches of the raised beds.  So that’s less effort, but it’s still takes a lot of time.

And this year, I’ll be growing parthenocarpic cucumbers and zucchini (Post G22-013) under insect netting.  So I’ll have one bed where an irrigation system is almost a must.  I don’t want to have to pull back the netting every couple of days in order to water that bed in the heat of summer.

In any case, after two years of toting buckets during the hottest part of the summer, this year I’m installing a drip irrigation system.

Up to now, I hesitated to do that, because:

  • I wasn’t sure if I was going to keep gardening after the end of the pandemic.
  • It seemed like a lot of bother for a few square feet of garden.
  • Buckets and watering cans work, and are good exercise.
  • This means bringing yet more plastic into my garden, which means disposing of that plastic, once UV-deteriorated, some years from now.
  • Undoubtedly the only parts I can get will be Made in China.

But mostly it was because:

  • I had no clue how to make that work.

In particular, I use both water barrels and municipal water to keep my garden going (per the table above).  I need a system that will work with both water sources.  It has to work with the nearly-zero water pressure of a gravity-fed rain barrel system, and with the (possibly reduced) pressure from the town water mains.

That, plus general ignorance of the topic, was enough to keep me schlepping pails of water for the past two years.

But after reading up on this, and filling up and abandoning a lot of on-line shopping carts, I think I finally know enough to cobble together a system that will work for me.

The first key realization is that almost nothing designed for a normal (that is, pressurized) irrigation system will work well with a low-pressure water-barrel system.  Without going into detail, some stuff (e.g., “pressure-balanced” anything) literally won’t work.   Other things might or might not work, depending on the specific parts that I buy.

And the reverse is also true.  A tame drip at 1.5 PSI becomes a sprinkler at 25 PSI.  Or simply blows apart the various hose couplings at that pressure.  And the likelihood that I can use one set of pipes to achieve a balanced flow at 1.5 PSI and 25 PSI seems pretty low.

The second key insight sounds stupid, but it took me about two years to figure this out.  I kept thinking that I needed a system that could work with either rain barrels or municipal water (with some sort of pressure reducer).  At some point, I even considered putting in two parallel systems, which would be a lot of work and wasteful to boot.

Have you figured out the simple solution yet?

I don’t need to run this at two pressures.  I can just fill the rain barrels with municipal water, and use one low-pressure irrigation system for both rain water and municipal water.  (I run the municipal water through a charcoal filter to remove chloramines before I use it.)

This is what is known in my family as “put the kettle on the floor and use Theorem 1”.  It comes from an old joke about asking a mathematician how to make tea, starting with a cold, empty tea kettle sitting on the floor.  (Take it off the floor, fill it, put it on the stove, heat it to boiling, pour it over tea leaves).   When asked how to make tea, with a kettle full of boiling water sitting on the stove, the mathematician’s answer was to empty the tea kettle, put it on the floor, and use Theorem 1.

The way to eliminate the need for a dual-pressure irrigation system is to take that nice, clean, treated, expensive city water, and put it into my less-than-pristine old rain barrels.  Once you get over the shock of that, it all makes sense.  That way I can distribute that water through the existing and (hopefully) fine-tuned low-pressure irrigation system.  And there’s no need for a pressurized water irrigation system at all.

I can’t believe it took me two years to realize that.


Irrigation systems using pressurized water are pretty much point-and-shoot affairs.  Run some tubing of a reasonable diameter, and then almost any type of “emitter” will work.  Anything from soaker hose to sprinkler heads to whatnot.

By contrast, a low-pressure irrigation system — gravity-fed from rain barrels — is more of a one-off piece of engineering.  You only get about 0.5 PSI per foot of elevation.  You might have, at best, one or two PSI of pressure, to run the entire system.

For sure, there aren’t going to be any sprinkler heads in my system.

Even with that limitation, it’s easy enough to use a rain barrel to irrigate a single plant or small area.    Right now, I have a potted lime tree hooked up to the nearest water barrel, via a filter, timer, and a garden hose with some nail holes punched in it.  The filter keeps the junk in the barrel out of the timer.  The timer periodically opens a valve to let the water flow.  And when it does, the plant gets a gentle sprinkling of rain water around the circumference of the pot, for a minute or two.

Want more water?  Hammer in a few more nail holes, or leave the timer on longer. It’s straightforward.  Idiot-proof, even,

Doing a larger area is far more complicated.  You want to get uniform water distribution over a large area, but the water pressure drops the further you are from the water barrel, or the higher the elevation of the raised bed.  Nail holes in a garden hose just won’t cut it.

In addition, most parts designed for pressurized irrigation systems won’t work on a gravity-fed rain barrel system.  Most sprayers, bubblers, emitters, drippers, timers, and so on are designed to work with a minimum of maybe 10 PSI.  There are some bubblers made for low-pressure systems.  But (e.g.) anything that says “pressure compensated” likely won’t work for a rain-barrel system, because they pressures they have in mind are far higher than what a gravity-fed system can achieve.

Given all the uncertainty, I’m just going to buy tubing, and poke holes in some of it, in a fairly systematic way.   No bubblers, emitters, sprinklers, soaker hoses, and so on.  Just tubing, with holes poked in it.  I think that’s about the limit of what I’ll be able to understand.

Plus, that’s about the cheapest way to go about this.  One roll of 1/2″ tubing to delivery water down the length of each bed, then 1/4″ tubing (with holes in it) to drip the water into the bed.  A filter, some fittings, and a hole punch should be about all I need.

It looks like the process of setting up one of these is reasonably idiot-proof.  If you don’t have enough water, make more holes in the pipe.  If you have too much water, plug the holes with “goof plugs” sold specifically for that purpose.  Keep the runs of pipe as short as possible, use larger pipe (1/2″) to deliver water along the bed, and smaller pipe (1/4″) with holes to drip the water into the bed.

In the end, it’s not rocket science.  Water flows downhill.  I just have to give it a way to get from the barrel, to the raised bed, in a controlled fashion.  The trick is to avoid all the fancy stuff that works with pressurized systems, and to realize that nothing bars me from running municipal water into my water barrels, and from there, through my low-pressure irrigation system.

I’ll let you know how things work out.


Post G22-015: First test of tote-based food dehydrator, version 2


Construction details are given in Post G22-014.

Bottom line:  Works just fine if you ventilate it with a computer fan.  Leaving this outside on two consecutive chilly, dry, sunny days was adequate to get 1/4″ potato slices dry enough to snap crisply when bent.

It was a little cold yesterday for solar food dehydration, not expected to top 60F.  But it was sunny and dry.  And that was enough to let me test and refine my revised tote-based food dehydrator (Post G22-014).   This is nothing more than an under-bed plastic tote with a bit of radiant barrier insulation outside, some cheap cooling racks inside, and a few holes in the top connected to thin plastic pipe.

Continue reading Post G22-015: First test of tote-based food dehydrator, version 2

Post G22-014: Plastic tote food dehydrator, version 2: Construction.


Edit:  See Post G22-015. Skip the drying racks, just place the food directly on the floor of the tote.  Replace the ventilation “chimney” with a computer fan.  With those changes, two days in the sun produced perfectly dry potato slices.

Last fall I came up with what I hoped would be a cheap and simple solar food dryer capable of drying tomatoes in the humid climate of Virginia. Continue reading Post G22-014: Plastic tote food dehydrator, version 2: Construction.

Post #G22-013: Toward a theological and horticultural theory of parthenocarpic zucchini.

Theological and horticultural background

A parthenocarpic plant is one that produces fruit without fertilization, that is, without pollination.  The resulting fruits are sterile and lack fully-developed seeds.

Without getting into the deeper theological aspects, the word derives from the Greek “parthenos”, meaning virgin.   And “carp”,  meaning to complain.  Thus,  the Parthenon is a temple to Athena, who was virgin who had few complaints.

(Technically, carp means seed.  So parthenocarp means “virgin seed”.  I like my version better.)

Of course, now that you know the word, examples crop up everywhere.  The banana is almost surely the most familiar example of a parthenocarpic fruit.  If you’ve ever wondered why bananas are seedless, now you know.  It’s due to their parthenocarpic nature.

Every parthenocarpic fruit is more-or-less seedless, but not every seedless fruit is parthenocarpic.  Some still require fertilization, they just don’t (or rarely) produce fully mature seeds.  Seedless watermelons fall into that category.  Unlike true parthenocarpic plants, seedless watermelons must be pollinated to bear fruit.  The term of art there is “stenospermocarpic”, which seems to be Greek for narrow fertilized seeds.

This is also not to be confused with plants that require pollination, but not pollinators Those include plants that are “wind pollinated” (like most cereal grains), and plants that may be “self-pollinating” due to perfect flowers containing both male and female parts, so that simply shaking the flower may sometimes pollinate it.  (This is the source of the electric toothbrush hack for ensuring good tomato pollination.)

Parthenocarpic cucumbers and summer squash.

Greenhouse and poly-tunnel farmers provide the commercial demand for parthenocarpic varieties of common garden plants such as cucumbers and squash.  In those enclosed environments, without bees, those crops would otherwise have to be pollinated by hand.  That’s an obviously labor-intensive step, and may be a practical impossibility for crops grown under low “hoop house” type row covers.

Several different varieties of parthenocarpic cucumbers and squash are available to the U.S. home gardener. I’ve been compiling a list, but I’ve limited it to the small subset of fruits that appear more-or-less identical to their seeded, pollination-requiring cousins.  The subset of interest to me includes:

Cucumbers:  H-19 Little Leaf, Corintino, Dive, Excelsior, Piccolino, Quirk

Squash: Venus, Part(h)enon, Burpee’s Sure Thing, Defender, Duntoo, Dunja, Cavili, Golden Glory.

(Parthenon or Partenon, sure.  But Venus?  Singularly inappropriate.)

As far as I can tell, these are exclusively F1 (first-generation) hybrids.  (Because, seedless, right?)  So if you will only grown heirloom plants, or those from which seeds can be saved, this is not for you.

To determine which varieties to grow I will apply the Tomato Paralysis cure from Post G22-001.  List in hand, I’ll cruise the seed racks at my local garden center and grow whichever of those they carry locally.

As a bonus, I can have my very own guilt-free arena of death.

I ended up here because I had such a dismal time trying to grow cucumbers and summer squash for the last couple of years.

The squash vine borer is present in this area (Virginia Zone 7) for a couple of months.  That is, more-or-less for the entire squash growing season.  If you restrict yourself to relatively short-lived pesticides (I used spinosad), controlling it requires careful spraying at five-to-seven day intervals. See Post #G27, A Treatise on the Squash Vine Borer.

The cucumber beetle was essentially absent from my first year of gardening, and I had a bounteous crop of cukes.  But by my second year I had built up an unstoppable population of them, and got almost no cucumbers whatsoever.  I never found a way to control the cucumber beetle that a) worked and b) was acceptable to me, in terms of environmental impact.

The damned things are like vampires:  All it takes is one bite.  Cucumber beetles spread bacterial wilt.  So it’s not the actual leaf and blossom damage from their feeding that matters.  It’s that any feeding at all infects the plant and kills it.  As far as I can tell, a) once bacterial wilt starts, it’s just a short while until the entire cucumber plant is dead, and b) “wilt-resistant” cucumber varieties aren’t, they end up just as dead as non-resistant varieties.

But if I don’t need pollinators, I can grow summer squash and cucumbers under insect netting/row cover.  In theory, if I can sterilize the soil under the plants (with a neem oil soil drench, perhaps), and keep a bug-proof enclosure over the plants, I can physically prevent those pests from reaching the plants.  And yet have a crop, because barring the bees entry does these plants no harm.

I’ve been hesitant to try this.  Not just because it seems like a lot of work to set up, and a lot of hassle to maintain.  But because of the “vampire” nature of cucumber beetles.  It’s not their feeding that matters directly, it’s the disease they carry.  If a single beetle breaches the defensive perimeter, it’s game over for the cucumbers.  Do I really think I can (e.g.) lift the cover off to pick the ripe fruit and set it back again without letting in a single cucumber beetle?

It seemed to be a fairly non-robust setup.  I understand that insect netting can greatly reduce insect damage.  But because of the nature of the beast — bacterial wilt — I really need to eliminate it entirely.  If the endpoint is going to be a bed of deceased cucumber plants, I know ways to achieve that with a lot less effort.

But if the bees and butterflies can’t get in … then nothing bars me from making that enclosed garden bed an arena of death.  All of those highly-effective (i.e., deadly) pesticides that I normally won’t touch due to bee toxicity are now back on the table.  Subject to some constraints, nothing need stop me from hosing the bed down with (e.g.) pyrethrins on a regular basis (subject to controlling runoff).  This means I can install a secondary, chemical line of defense beneath the primary (physical) barrier.   If need be.

I’m looking for parthenocarpic, not carcinogenic.  So it’s not like any pesticide is fair game.  But cheap, short-lived and effective organics like pyrethrins would seem to be plausible.  Once I screen in the bed, I no longer have to worry about killing off my local bees and butterflies.  More-or-less any bug that gets through the outer defenses is fair game.


Anything worth doing is worth over-doing.  Given how much hassle it’s likely to be to do this at all, I think I’ll go for more, rather than less.

My plan is to dedicate one entire raised bed to parthenocarpic cucumbers and squash.  Roughly 4′ x 16′ or so.

Plausibly the major expense will be for the requisite statue of Athena, so that I may dedicate my parthenocarpic garden appropriately.  And some large-economy-sized Bucket-o’-Death, to ensure that any bug making it past the cover will die ASAP.

Otherwise, for me, this requires no investment in materials.  I already own a more-than-lifetime supply of thin floating row cover.  As well as a pile of loose PVC pipe and fittings, which is to adults what Tinker-Toys are to kids.

A year ago, I didn’t even know that such a thing as parthenocarpic squash existed.  This year, I’m going to grow a bed of it.   I’ll let you know how it turns out.


Post G22-011: Canning lids, from shortage to wide-mouth surcharge.

Above:  Used Ball lids.  The one on the left clearly shows the groove left by the canning jar.  The one on the right was boiled for 20 minutes, which flattened that groove considerably.  I picked up this tip boiling lids if you plan to re-use them from the blog A Traditional Life.

One of the many U.S. shortages that occurred during  the COVID-19 pandemic was a shortage of lids for use in home canning.  I’ve posted extensively on that here. Continue reading Post G22-011: Canning lids, from shortage to wide-mouth surcharge.

Post G22-010: Energy required for various methods of preserving tomatoes at home.


Source:  Wayfair

The vacuum sealer is that rare device that serves as both a kitchen appliance and a source of entertainment.  Every time I run my new Nesco VS-09, I practically want to applaud when it finishes.

I don’t normally give much thought to air.  Until it’s all gone.  Then the arithmetic of 15 pounds per square inch leads to the realization that this goofy little countertop appliance generates a literal half-ton of crushing force on a 6″ x 10″ pint-sized bag.

But I digress.  I actually bought this for the serious purpose of preserving garden produce.  The fact that I find the process and results to be so entertaining is just icing on the (perfectly flat half-inch thick piece of) cake.

In any event, there is a serious purpose to this post.  And that is to show that if you have a freezer that’s already running, then freezing your tomatoes is by far the most energy-efficient way to preserve them.  The only method that would beat that is solar drying, and I haven’t quite figured out how to do that well in my humid Virginia climate.


Tomatoes as freezer free-riders.

The last thing I need is another kitchen appliance.

But I bought this vacuum sealer anyway, after thinking through all the food preservation I did last year.  Of all the pickling, canning, drying, and freezing, by far, the tastiest, most garden-fresh results came from freezing.  With drying (dried tomatoes) a close second, due to the intense flavors that produces.

And so, purely from a quality standpoint, for tomatoes to be used in soups and stews,  my wife and I agree that freezing is the best option.  It preserves that fresh tomato taste. But how does it stack up in terms of energy use?

Freezing gets a bad rap, as a means of home food preservation, for its relatively high energy use.  But I think that’s not entirely correct.

If you run a freezer expressly for the purpose of preserving garden produce, then, sure, I’d bet that freezing has a fairly high energy cost.  In that case, you’d have to pro-rate the annual electricity use of that freezer over the pounds of produce preserved.  (Because, by assumption, you wouldn’t be running that freezer if you weren’t using it to preserve your garden produce.)

Just tossing out some round numbers, based on past experience, I’d bet that a typical 15-cubic-foot chest freezer has enough space to store 300 pounds of produce, and consumes about 300 kilowatt-hours (KWH) of electricity per year.

So, roughly speaking, if you run that freezer because you use it to preserve your produce, you’d consume about 1 KWH of energy for every pound of produce preserved. 

By contrast, if you are already running a freezer, and will continue to run it regardless, and you have the space, then freezing your produce only costs you the energy needed to freeze it in the first place.   The cost of running the filled freezer doesn’t count, because you’d bear that cost in any case.

My fridge comes with a big freezer.  It’s not like I’m planning to unplug that any time soon.  And so, I’m perfectly happy to let my frozen garden produce be a free rider here — taking advantage of the fact that the freezer is running, but not being asked to “pay” for it.

In that case, the only additional energy cost is the cost of getting the room-temperature produce down to the 0 F temperature of the freezer.  Given that  (e.g.) tomatoes are 94% water, that’s more or less the energy required to bring one pound of room temperature water down to 0 F.  Including the one BTU per pound required to cool the water, and the 144 BTUs per pound required to convert to ice, that works out to (70 + 144 =) 214 BTUs, or (at 3.4 BTUs per watt-hour) 63 watt-hours.  So, if you are just tossing your produce into a freezer that is going to be running in any case, freezing it takes 0.063 KWH for every pound of produce preserved.

You might think that’s a bit of a cheat, because one way or the other, you’ll want to peel those tomatoes before you use them.  The most typical methods for peeling them involve heat (either boiling water, or holding them in the flame of a gas stove).  But — surprise — it’s actually a snap to peel them after they’ve been frozen, per this YouTube video.

Take a look around 47 seconds into that video.  My jaw dropped just after the tomato did.  I know the term life-changing is overused, so let’s just say this was a tomato-life changing revelation for me.  As in, I’m never going blanch and peel a tomato ever again.  Arguably, it may actually take less energy to freeze-and-peel than to blanch-and-peel, what with the energy costs required to boil the water and cool the tomato afterwards.

Other preservation methods

I have already tracked the energy costs of preserving by canning or drying, in various earlier posts.  Let me bring all of that together in one place, below.

Drying tomatoes in my four-tray Nesco dehydrator consumed 8 KWH of electricity (per Post G21-049).  That was in the humid outdoor Virginia summer.  I am fairly sure that each tray can hold less than a pound of quarter-inch-thick tomato slices,, but a) I could stack up to 12 trays at a time for drying, and b) those were very “wet” slicing tomatoes, not the paste tomatoes that are normally used for drying.  That said, for illustration, let me just assume one pound per tray, four trays, yield 2 KWH for every pound of produce preserved.

Canning tomatoes in a water-bath canner consumes a considerable amount of energy as well.  I did the full workup on the energy cost of home canning two years ago, in Post #G22.   I had to do that because, as far as I can see, the rigorous research literature on this crucial topic looks like this:


In any case, the all-in energy cost for canning five quarts of pickles, on a gas stove, in an air-conditioned house, was 5528 kilocalories (kcal).

Source:  Post #G22.

Per the USDA guide to home canning, quarts of pickles require a much shorter processing (boiling) ,time (15 minutes) compared to quarts of tomatoes (45 minutes) in a water-bath canner.

Based on my prior calculation (shown above), I need to add another 800 Kcal to account for that, bringing the total up to 5300 Kcal for 5 quarts (= 10 pounds) of tomatoes.  At 1.16 watt-hours per kilocalorie, that works out to be 0.6 KWH for every pound of produce preserved.

I should note that this is a little conservative, because you have to peel the tomatoes first.  That’s going to involve a little additional boiling time.  But with all the boiling that’s taking place with the canning, I figured that was more-or-less rounding error.

Finally, I can take a rough guess at the energy cost of my crock-pot spaghetti sauce.  Crock-pot spaghetti sauce (Post #G21-048) absolutely minimizes the labor input, and is idiot-proof to boot.  But it requires processing tomatoes in both a pressure cooker (briefly) and a crock-pot (overnight).  For four quarts (eight pounds), the crock-pot portion uses about 4 KWH. But the pressure-cooker portion (20 minutes at pressure) likely used almost as much energy as canning, so for four quarts I need to add one-third of my pickle canning estimate above, which, by the time all the arithmetical dust has settled, adds another 2 KWH.  Or a total of 6 KWH for 8 pounds of tomatoes, or 0.75 KWH for every pound of produce preserved.

There’s no additional energy cost for peeling in this method, because the entire batch of tomatoes is run through a Foley mill after pressure-cooking.  That takes out the peels and (most of) the seeds.

Let me now produce the nice neat table of energy required for food preservation, all of it expressed in terms of KWH of energy per pound of produce preserved.

All of that comes with some caveats.  The canning was done on a gas stove in an air-conditioned house.  The drying was done outside, in humid air.  I could dry up to twelve trays at once, instead of the four that I already owned.  Maybe there’s a little more energy required for the blanch-and-peel step in some methods.  And so on.

Nevertheless, the results are so clear as to be undeniable.  (So clear that I double-checked that freezer math a couple of times).  If you have space in your freezer, and you’re going to run that freezer anyway, by far the most energy-efficient way to preserve tomatoes is to toss them in the freezer.  And, per that YouTube video above, peel them as you thaw and use them.

I surely need to mention the one common method that isn’t on the list, solar (or open-air) drying.  Plausibly that has zero energy cost, but I have not (yet) figured out how to do that in my humid Virginia climate.  I’m already working on how I’m going to improve my simple $18 plastic-tote food dryer (Post #G21-049).  The solution might be as easy as “don’t overload it”.

Two minor caveats:   COP and GHG sold separately.

Two minor factors make this conclusion somewhat less that complete.  Those are coefficient of performance (COP) of a freezer, and the different rate of greenhouse gas (GHG) emissions for natural gas and electricity used in the home.  Near as I can tell, neither of these results in any material change in the relative efficiency of the various preservation methods.

First, this calculation isn’t complete because it doesn’t factor in the energy conversion efficiency or coefficient of performance (COP) of refrigerators or freezers.  The coefficient of performance for a heat pump is the amount of heat energy it can move, for a given amount of electricity supplied to it.  Almost all commercially-used heat pumps have a COP greater than 1.0.  That is, they can move more than 1 KWH of heat energy for every KWH of electricity they consume.  COPs for modern AC or heat pump units typically run around 2.5 to 3.5 (per the link above).

The estimate above — 0.063 KWH — is the amount of heat that needs to be (re)moved from the interior of the freezer.  It will actually take less than 0.063 KWH to do that, because fridges and freezers are just another form of heat pump with a COP greater than one. While Wikipedia (cited above) assures me that they have a COP greater than 1.0, I have yet to find a source that will pin that down further. The best I’ve found is a passing reference to a COP of around 1.0 for a deep freeze unit (per this reference).

The bottom line is that a typical home freezer might use somewhat less than 0.063 KWH to remove 0.063 KWH of heat energy from its interior.  But how much less, I can’t find the source that will let me pin that down.  I suspect that, given the large temperature differential between interior and exterior, the COP of most freezers isn’t much higher than 1.0 or so.

Finally, KWH is not the same as GHG (greenhouse gases).  This only measures energy consumed within the home, and does not differentiate between natural gas and electricity.  Fossil-fuel based electrical generation is far from 100% efficient, so the actual amount of fuel consumed (to generate the electricity) is a low multiple of the energy actually delivered to the house.  But in addition, electrical generation consists of a mix of generation sources, some of which create greenhouse gases, some of which do not.  If the ultimate question is one of carbon footprint, we’d have to modify this calculation, treat electricity and natural gas separately, and then redo it for some assumed electrical generation mix.

That said, when I take a rough cut at the difference between natural gas (burned in a stove) and electricity (produced with a typical U.S. generating mix), I’m not sure that adjusting for each fuel type separately would make much difference.

Natural gas releases 100% of its energy within the home.  But a typical natural gas stove is only about 40% efficient.  That’s the energy that goes into whatever you are trying to cook, with the rest simply serving to heat up the kitchen.  Basically, for every 100 units of C02 produced, you get 40 units of usable energy from your gas stove (Whatever units might mean, in this case).

For electricity, by contrast, the amount of fuel burned at the generating plant is far more than the amount that makes it into your home.  But once it gets to your home, I’ve either directly measured 100% of what was consumed, or the theoretical calculation (for freezing) should be close to that.  And so, as with natural gas, for every 100 units of C02 produced in generating electricity, you get X units of usable energy in the home.

The problem is that X depends on the generating mix that feeds your particular section of the grid.  Even so, let me do the arithmetic for Virginia’s electrical grid.

Last time I checked, Virginia’s electrical grid released 0.7 pounds of CO2 per KWH of electricity delivered.  Starting from that, I’m going to compare C02/KWH of usable energy for the Virginia grid versus a 40 percent efficient gas stove.

The EPA shows that burning a therm of natural gas releases an average of 0.0053 metric tons of C02.  At 2204 pounds per metric ton, that’s 11.7 pounds of C02 per therm.  A therm is 100,000 BTUs, and there are 3.4 BTUs per watt-hour.

Slapping that all together, burning a therm of natural gas produces 11.7 pounds of C02 and 29.4 KWH of (heat) energy, or 0.4 lbs C02 per KWH.

But a natural gas stove is only 40% efficient.  A stove has to use (1/.40 =) 2.5x as much natural gas to deliver that usable KWH of heat.  The bottom line is that a 40 percent efficient natural gas stove releases 1.0 pounds C02 for every usable KWH of heat delivered in the home.

And so, per KWH of usable energy, in terms of GHG emissions, electricity (in Virginia, at 0.7 lbs C02 per usable KWH) is slightly cleaner than natural gas burned in a (typical) 40 percent efficient stove.  But only slightly.  So the electrical options actually perform a little bit better than shown in the table above, relative to the gas-stove-intensive canning. 

There’s nothing in any of that to change the conclusion that tossing your tomatoes into a freezer that would be running in any case is by far the most energy-efficient way to preserve them.

So, what about that vacuum sealer?

All of the above brings me back to my new toy, the vacuum sealer.  If I’m going to freeze my tomatoes, the binding constraint is now the space they take up in the freezer, and secondarily, the length of time they’ll last once frozen.  Both of which will be best addressed by vacuum-sealing them.

Most sources suggest that you freeze the tomatoes before vacuum-sealing.  But at least one source shows tomato chunks that were vacuum-sealed and then frozen.  That’s what I’m now aiming to do, only using whole tomatoes, not chunks.  Given the literal tons of force that one of these sealers can generate, I’ll have to use the setting that allows the strength of the vacuum to be controlled manually.  In the end, I’m aiming for a freezer stocked with nice, flat, well-preserved packages of energy-efficient frozen tomatoes.

With any luck, we’ll see how that all plays out in a few months.


Post G22-009, the second-biggest waste of time in the U.S.A.

Traditional, unconditional, last-frost date

I had planted a few cold-hardy vegetables in my garden weeks prior to last weekend’s deep freeze.  I put in some snow peas, potatoes, beets, garlic, onions. 

It got down below 20F briefly on one of those nights.  I can now say that all of those appear to have survived, with just a bit of TLC.   That was in the form of capping the bed with radiant barrier, then adding a piece of plastic for air-tightness.  (See Post G21-018, or my just-prior garden posts.)

It’s no surprise that we had a freeze.  Our nominal “last frost date” is somewhere around April 22,so these plants were in the ground almost two months ahead of that.  Instead, the interesting thing is that I had two weeks’ warning that the freeze would occur.  The fourteen-day forecast accurately predicted that there would be a freeze that weekend, although the original forecasts understated the depth of that freeze.

This leads me to ponder the implications of reasonably-accurate long range weather forecasting and our “last-frost” dates.  Folklore guidelines (“plant peas on St. Patrick’s Day”) and science-based “last frost date” guidelines predate the era of supercomputers that make long-range forecasting possible.   Weather is still chaotic in the mathematical sense, and so not predictable at very long intervals, but we now have two-weeks-ahead temperature forecasts that are reasonably accurate.

I already rang the changes on this once, in post G21-005, Your 70th percentile last frost date is actually your 90th percentile last frost date.  What you typically see cited as your “last frost date” is the date on which, historically, frost only occurred after that date around 30 percent of the time.  But that’s an unconditional probability, as if you would plant on that date regardless.  If, by contrast, you check your 14-day forecast on that date, and refrain from planting if frost is in the forecast, then you’ll convert that to a 90th percentile last-frost date.  That conditional probability — chance of frost after that date, conditional on a frost-free 14-day forecast — gives you a much higher chance of avoiding a freeze after that date.

The upshot is that a reasonable prediction of the two weeks following the “last frost date” shifts the odds attached to that date considerably.  It’s actually a lot safer to plant frost-sensitive plants on that date, in the modern world, than it was in the era when no forecasts extended more than three days.  As long as you make that decision conditional on the extended forecast, and you’re smart enough not to plant if it looks like frost any time in the next two weeks.

At present, we’re creeping up on 14 days prior to our April 22 “last frost date”. And I’m pondering — just as an exercise in probability and statistics — whether that same math works 14 days in advance of the date. 

And I’m pretty sure it does.  If the 14-day forecast were completely accurate, then the conditional 70th percentile last frost date in this area would be April 9th.  No frost in the forecast through April 22 would mean that the conditional odds of frost occurring after April 9 would be the same as the unconditional odds after April 22.

That is, April 9 is our conditional 70th percentile last frost date.  If we have a decidedly frost-free 14 day forecast at that point, planting on that date bears the same risk of frost damage as planting blindly on April 22.

The only uncertainty there is in how accurate the 14-day forecast actually is, for daily low temperature.

Weather forecasts seem to be one of the few true ephemera of the digital age.  They are published, and then they are replaced with the next day’s forecast.  Nobody cares about yesterday’s forecast, other than those who have some deep professional interest in forecast accuracy.  Accordingly, where you can look up the actual weather 14 days ago, I haven’t yet located a database that lets me look up the actual weather forecast 14 days ago.

So that’s going to have to remain an unknown, for the time being, unless I want to try to compile the data, for my location, day-by-day, myself.  Or if I can find existing research that addresses this exact question of predicting a frost.  So I’ll just have to leave that as saying that if the 14-day forecast shows lows that are well above freezing, then you can probably move your traditional (unconditional) 70th percentile last-frost date up by two weeks.

But is this just the second-biggest waste of time in the U.S.?

The second-biggest waste of time in the U.S.A. is doing something really well that doesn’t need to be done at all.  (I heard that in a time-use seminar I attended decades ago.)

In the fall, frost protection has some clear advantages.   The plants are already grown, the produce is already ripening.  Protection from an unexpected early frost is a matter of saving garden produce that would otherwise be lost.

But as I hustle about protecting my plants in the spring, it invites the obvious question:  Just how much am I gaining by planting these crops early? And to that, I will add not just planting early, but the whole process of starting seeds indoors, regardless of the planting date.

In reality, is this really just an example of the second-biggest waste of time in the U.S.?

Ultimately, while some plants may grow in the cold, they tend to grow slowly.  At some level, that’s just basic chemistry.  The rate at which a typical chemical reaction proceeds roughly doubles with every 10 degrees C of temperature increase.  Sure, plants will develop enzymes to speed those processes in colder temperatures.  But it doesn’t take a genius to notice that while they will grow, they sure won’t grow very fast.

What prompts this is my peas, which are now all of about 2″ high.  And it’s getting on close to a month after they went into the ground.  Is  that head start worth it, compared to simply waiting for the nominal last-frost date and planting them then?

In short, I’m beginning to suspect that my current setup — plant early, provide frost protection, but no greenhouse — might just be the least efficient of all possible worlds.  All the hassle of early planting, and (almost) none of the benefit.

Without a greenhouse structure (or poly tunnel, or similar) to warm the daytime air and soil temperatures, it seems like most of what I’ve done is to induce my plants to try to grow under inhospitable conditions.  And they are responding accordingly.

Back when I was a low-effort gardener, I seldom mucked around with any type of early planting.  I’d start seeds a couple of weeks before I planted them, just to be able to have a tiny visible plant to stick in the ground.  (And so, have better chance of survival for (say) tomato plants.)  But my opinion then was that the gains from very early planting were minimal.  Give it a couple of weeks, and the (e.g.) peas planted later in the year will have effectively caught up with those planted earlier.

As a result, I’m now wondering whether I’ve been taking all this early-planting advice from people who do early planting and have some type of greenhouse arrangement on top of those early plantings.  From what I’m observing so far, that would make a lot more sense than just sticking plants in the ground and protecting them from freezing as needed.

When I briefly Google for this topic, all I see is people touting the benefits of early planting.  In effect, a series of statements that you’ll get more out of your garden if you do it.  I’m not seeing any quantification of just how much more you get, from early planting alone (i.e., with frost protection but not a greenhouse or poly tunnel).

So, before I get any further caught up in this effort to see just how much I can push that last-frost date, and just how well I can protect those tender plants from frost, it seems like I need to assess the cost/benefit tradeoff.

I’ve proven that I can plant well in advance of that last-frost date.  I can do that very well, thank you.  But should I do that?  I don’t think I’ve really answered that question.  And, in particular, should I do that without some sort of setup to warm the daytime air and soil temperatures?

Maybe early planting without a greenhouse really is just the gardening equivalent of the second-biggest waste of time in the U.S.A.  Clearly, that needs to be the next thing I test.  For that, I need some sort of cheap, safe, low-effort greenhouse or poly tunnel.  One that minimizes the chances that I’m going to bake my plants to death.

So that’s the next thing on the agenda.  Replant what’s in my garden, one month after the original planting date. And work up a greenhouse covering that, as a lazy gardener, I can live with.